Physical vapor deposition (PVD) processes can use radio frequency (RF) energy to enhance substrate processing for certain applications. For example, RF energy may be provided to a target of a PVD chamber to facilitate sputtering of materials from the target and depositing the sputtered materials onto a substrate disposed in the PVD chamber. The inventors have observed that process non-uniformity issues, such as non-uniform film deposition, may arise in such PVD chambers under certain operating conditions. The inventors believe that such non-uniform film deposition may occur due to a change in deposition rate across a substrate over the course of the life of a target.
Accordingly, the inventors have provided improved methods and apparatus for maintaining low non-uniformity over the course of the life of a target.